1. Field of the Invention
The present invention relates to an ink-jet head for squirting ink at recording medium for recording a formed image and the like.
2. Description of the Related Art
In the ink-jet head, ink from an ink tank is supplied to a pressure chamber through a common ink chamber, to impart squirting energy to the ink in the pressure chamber and then the energized ink is squirted from a nozzle. The head is provided with an actuator for imparting the squirting energy to the ink in the pressure chamber. The actuator is electrically connected to a flexible printed circuit (FPC). The actuator is driven under driving signal fed from a driver IC through the FPC.
A variety of actuators are in use, including a piezoelectric actuator and a capacitance type actuator. In the piezoelectric actuator, the actuator is disposed opposite to the pressure plate to form a partition wall of the pressure chamber, so that when the actuator is mechanically deformed, the pressure chamber is changed in volume to thereby impart the squirting energy to the ink in the pressure chamber. In the capacitance type actuator, a vibrating sheet is disposed to form a partition wall of the pressure chamber and the actuator is arranged to be spaced apart from and opposite to the vibrating sheet. When the vibrating sheet is deflected by electrostatic force generated by the drive of the actuator, the pressure chamber is changed in volume to thereby impart the squirting energy to the ink in the pressure chambers, as is the case with the piezoelectric actuator mentioned above.
Although there are presented a variety of actuators, including those as mentioned above, the existing actuators all suffer from the problem that when the ink adheres to the actuator, the ink squirting capability of the actuators reduces or fails. In order to minimize this problem, various techniques have been developed. Take an actuator having such a structure that FPC is bonded to the actuator and is further drawn to an outside of the head, for example. For this type of actuator, there has been proposed a technique of mounting a sealing member at a location where the FPC is drawn out, because the ink enters into the head from that location easily. According to this technique, the sealing member prevents the entry of the ink into the head, thus preventing the adhering of the ink to the actuator.
However, according to this technique, although the adhering of the ink to the actuator can be prevented, there is a possibility that the sealing member may enter into the head to cause adherence of the sealing member to the actuator. When the sealing member adheres to the actuator, the deformation of the actuator, the piezoelectric actuator in particular, is deteriorated. Further, in other types of actuators, such as a capacitance type actuator, as well, when the sealing member adheres to the actuator, the function of the actuator may deteriorate, as is the case with the actuator of the type noted above. Therefore, the existing techniques mentioned above are unsatisfactory for solving the problem of reduction of the ink squirting capability of the actuator.